Brick-lined, water-cooled industrial furnace door



BRICK-LINED, WATER-COOLED INDUSTRIAL FURNACE DOOR Filed April 9, 1962 2Sheets-Sheet 2 0/71 l5 Q 57 542 I3 "ff" 1! 3% l5 21 I 5 14 I I g- '9 31+58 27 :2 INVENTOR.

OTTWIN LBRAUN. 25

ATTORNEYS.

United States Patent 3,212,478 BRICK-LINED, WATER-COOLED INDUSTRIALFURNACE DOOR Ottwin L. Braun, Pittsburgh, Pa., assignor to RelianceSteel Products Company, McKeesport, Pa., a corporation of PennsylvaniaFiled Apr. 9, 1962, Ser. No. 186,265 7 Claims. (Cl. 122-498) Thisinvention relates to a brick-lined, water-cooled, industrial furnacedoor, and more particularly to a watercooled door having a refractorybrick lining supported on the door by shelves secured to the door.

It is customary practice to utilize refractory-lined doors foropen-hearth furnaces to prevent failure due to the intense heat to whichsuch doors are exposed. In the past the doors of this type have eitherbeen lined with refractory brick, or with a refractory compound or ram.ming material bonded to the door by means of tie elements which arefirmly connected to the door but which are embedded for the most partwithin the composition. Such doors are often water-cooled by forming thedoor with hollow sections adjacent the lining for transfer of the heatencountered by the lining to a liquid within the hollow door sections.An example of one such door is that disclosed in my copendingapplication Serial No. 142,371, now Patent No. 3,156,218, filed October2, 1961, and entitled Forced Circulation Water-Cooled Furnace Door.

A refractory door lining in general use in open-hearth furnace doors iscomposed of a ramming material with a chromite base having a meltingpoint of about 3720 F. A door lining with a higher melting point isnecessary, however, for doors on open-hearth furnaces which employoxygen to augment the regular furnace fuel. A ramming material having amelting point in the order of 4950 F. would be desirable, butcharacteristics of such materials render them unsuitable for use underconditions experienced by doors of open-hearth furnaces wherein radicaltemperature changes and sustained high temperatures are encountered.Thus, one of the major problems encountered by those skilled in the artof furnace doors is that of providing door structures having liningswhich will resist flaking or disintegration due to the high temper-atureenvironment wherein these doors are employed, for if the lining isdestroyed the metal of the door is exposed directly to the heat of thefurnace and is also destroyed. Consequently, a door which can withstandhigh temperatures over a long period of time, that is, for repetitivefurnace heats, is highly desirable; otherwise, thedoor must be removedfrequently from the furnace for relining, an operation which normallyrequires a costly investment of time, material and labor.

The present invention provides a panel door for openhearth furnaceswhich has a lining of bricks of magnesite which are supported on ahollow section of the door by means of shelves. Upon exposure toelevated temperatures the shelf material and the magnesite brick, whichare metal clad, fuse together at their heat-exposed surfaces and form athin molten metallic surface. The magnesium core of the brick begins toflux under the intense heat and will bond to the molten metal. Thefusion of the brick material to the metal retards further melting ordistintegration of the lining the rate of transfer of heat from the doorlining to the coolant circulated in the hollow panel of the doorbalances the rate of melting of the door lining material.

It is an object of the present invention to provide a new and improvedwater-cooled furnace panel door having a brick lining.

Another object is the provision of a water-cooled 3,212,478 PatentedOct. 19, 1965 ice furnace door with a lining constructed of brickcourses which are layered on shelves removably positioned on the doorsuch that lining changes can be made by simply removing the shelves fromtheir assembly position on the door.

A further object is to provide a water-cooled furnace door having alining of elements which fuse together under heat of a furnace to form asurface layer adjacent the combustion zone of the furnace which retardsthe thermal destruction of the refractory material of the mug;

One modification of the instant invention may include a door havingbrackets fastened to one door face, shelves with depending tabs fastenedremovably to the brackets, and brick layered in courses supportinglyseparated by the shelves, the brick and shelves being fused by the heatof the furnace to form a lining with a surface which retards thermaldestruction of the lining refractory.

A complete understanding of the invention may be had from the followingdetailed description of a specific embodiment thereof when read inconjunction with the appended drawings, wherein:

FIG. 1 is a front elevational view of the door;

FIG. 2 is a sectional plan view taken along the line HII of FIG. 1;

FIG. 3 is a vertical sectional view taken along the line III-11l of FIG.1, which is the axis of symmetry of the door;

FIG. 4 is a rear view of the door;

FIG. 5 is a fragmentary enlarged view of the attachment between the doorshelves and the door back plate; and

FIG. 6 is an isometric view of a brick for use in making the door.

Referring now to the drawings, wherein like reference charactersdesignate like or corresponding parts throughout the several views,there is shown in FIG. 1, which illustrates a preferred embodiment, afurnace door 11 generally rectangular in shape with a planar front plate12 which, when the door is installed on a furnace, lies opposite theside of the door exposed directly to the furnace heat.

As customary in the art of open-hearth furnace doors, door lininginspection openings 13 and a furnace inspection port 14 are providedthrough the front plate 12 of the door 11, and, as best illustrated inFIG. 3, sealed to the lining inspection openings 14 are open-endedsleeves 15 which extend thnough aligned similar openings 16 in a planarback plate 17 spaced laterally from the front plate 12 so as to providean interstice or hollow portion 18 between the plates. The open-endedsleeves 15 terminate at the rear surface of the back plate 17. On theother hand, the furnace inspection port 14 is lined with a pipe 19 whichextends across the interstice 18 and through an aperture 21 in the backplate 17 which is coaxial with the port 14 through the front plate 12.As best shown in FIG. 3, the pipe 19 terminates at the rear surface ofthe back plate 17.

A flange 22 of U-shaped cross-section, FIG. 3, extends across the doorbottom and is of a heavier gauge steel than the steel of the remainingdoor structure to better withstand wear as the door bottom is repeatedlylowered in forceful contact with a door threshold of the furnace, notshown. The door back plate 17 has its periphery 23 turned toward therear and is inclined toward the door center. Across the door bottom theflange 22 is fixedly sealed, as by welding, to the terminal portion 24of the back plate periphery 23 in a manner such that the hollow portion18 between the door plates 12 and 17 is contiguous with a hollow section25 existing between the flange 22 and the periphery 23 of the back plate17. The side marginal portions 26 and the top marginal portion 27 of thedoor 11 are designed with a continuous channel 28 formed by turning ofthe side and top edge portions 29 of the back plate 17 outwardly fromthe door center. The front plate 12 has a r'earwardly directed flange 31which is suitably sealed to the outwardly turned side and top edgeportions 29 to complete the design of the channel 28. The channel 28 isin open communication with the hollow section 25 across the door bottomand with the hollow portion 18 between the spaced planar plates 12 and17.

By fashioning the door structure in the manner described, the door isproperly constructed as a hollow panel door. Within the hollow portionthereof a coolant, such as water, may be circulated to transfer heatfrom the door to avoid its mechanical and chemical destruction byintense heat. For this purpose a liquid for circulation may be force-fedthrough an inlet pipe 32 which passes through the top marginal portion27 of the door through top edge portion 31 of the front plate 12 anddepends in the channel 28 of the side marginal portion 26 to a pointabove the bottom hollow section 25. On the opposite side marginalportion 26 from the inlet pipe 32 is an outlet fitting 33 which extendsonly through the top edge portion 29 into communication with the hollowchannel 28 as depicted in FIG. 2. Plugged washout openings 34 areprovided through the side portions 26 of the door 12 and open into thebottom hollow section 25. By connecting a supply of water or othercoolant liquid under pressure to the inlet pipe 32, the hollow portion18, bottom hollow section 25, and top and side continuous channel 28 areflooded, and the fluid is circulated to the outlet fitting 33 underpressure of the force-fed coolant. Accordingly, the back plate 17, whichis adjacent the heat of the furnace when the door is in use, transfersheat from a lining tothe coolant for removal through the outlet fitting33, and the door lining is consequently cooled. The door is lowered andraised into position over the charge opening of the open-hearth furnace,for example, by suitable linkage means or cables connected to upstandingapertured lugs 35 and by a handle or eye member 36 fastener to the topof the door 12.

With the rigid frame of the structural panel door design having beentreated, the lining 37 of the door will now be explained with attentiondirected particularly to FIGS. 3, 4 and 5. As shown best in FIG. 3, arecess 38 is formed which is bounded by the re-entrant and rearwardlydirected periphery 23 of the back plate 17. Into this recess courses ofbrick 39 are placed to compose the lining 37. The brick 39 preferablyare the so-called metalcase type, that is, the brick 39 are wrapped by aband of steel about the flat surfaces of the brick exclusive of thebrick ends. The bricks are composed of the mineral magnesite, which ismagnesium carbonate, MgCO as found in nature. Such a brick is shown inFIG. 6 wherein the brick 39 has a metal wrapping 3911 about the longfaces. of the refractory body 3%, the ends being uncovered. Theparticular brick here shown is notched at 39a to clear a shelf bracketas hereinafter described, but this notch is required only in some of thebricks.

superposed on each single course of the magnesite brick 39 is a shelf 41which is either tack welded to the back plate 17, or fastened removablyto the back plate by spaced brackets 42 which are fixed to the backplate, FIG. 5. The brackets have a downwardly tapered opening 43 intowhich correspondingly tapered tabs 44 fit frictionally. The tabs 44 arein turn fixed, as by welding, to the lower surface of the shelf 41 atspaced intervals matching the spacing between brackets 42 fixed in-lineto the plate 17. The inner edge of each shelf snugly contacts the planarsurface of the back plate 17 to which they are fastened by either of thetwo mentioned techniques. The width of each shelf 41 is the same as thewidth of the metal-clad brick 39 such that the rear face of the lining,which is that surface to be directly exposed to the furnace heat, issubstantially uniform. The rear plate periphery 23 ex tends slightlybeyond the exposed surface of the lining to better key the assembledlining in position on the door. The bricks 39 are suitably notched toclear the brackets, bringing the face of each brick in contact with thesurface of the back plate 17 of the door.

In the assembly of the lining 37 within the recess 38 the first courseof metal-clad brick is laid adjacent the bottom of the recess, and ashelf may be tack welded to the plate 17 above the first course.Prefenably, however, the shelves are fastened to the back plate 17 intoplace above the first course by means of the tabs and brackets as abovedescribed. The courses of bricks and shelves are alternated until thelaying of the brick courses is completed to consume the volume of therecess. Next, the exposed rear surfaces of the metal casing of the brickare tack welded to the steel plate shelves 41, fixing the lining 37 as aWhole into position in the recess 38 for handling of the door prior toand during installation of the furnace.

When the assembled door with lining 37 is aligned on the furnace, theintense heat of the furnace radiating on the rear face of the lining 37melts the exposed shelf edges and the exposed metal casing surface ofthe brick, giving rise to a thin molten mass of the merged metals. Thehigh temperature begins to cause the magnesium of the magnesite brick tofuse and to merge with the molten metals. The cooling of the liningprevents further melting of the lining materials by the forcedcirculation system provided in the panel of the door; however, anequilibrium is established between the rate of melting of the liningmaterial and the rate of cooling of the lining. Thus, by theincorporation of the magnesite brick which has a high melting point in afurnace door lining the useful life of the door is prolonged over thatof the conventional bricklined furnace doors.

It is manifest that the above-described embodiment of the invention ismerely illustrative, and that numerous modifications may be made withinthe spirit and scope of the invention.

I claim:

1. A furnace door comprising a rigid hollow frame with a planar rearsurface having a recess, the frame being of a size and configuration tospan an access opening of a furnace in communication with the heatingzone of the furnace, the recess being of a depth equal to a dimension ofa clad refractory brick, metal shelves attached to the rear surface ofthe frame and within the recess at vertically-spaced intervals with theshelf outer edges being in a common plane which includes one wall of abrick placed thereon, the shelves being of lengths to span the recessand of widths substantially equal to the depth of the recess, andrefractory magnesite bricks with metal casings positioned in courses onthe vertically-spaced shelves, the magnesium of the magnesite brick, themetal of the exposed walls of the brick casings, and the shelf edgesbeing fused by direct exposure to the furnace heat to form a thin moltensurface layer across the recess whereby stability of the magnesite brickis maintained and the brick is preserved against heat destruction.

2. A furnace door as in claim 1 wherein the shelves are attachedremovably to the rear surface of the frame by tabs depending atintervals along the shelf inner edges and received within spacedbrackets fixed to the rear surface of the frame within the recess, andthe bricks are notched to fit snugly against the surface with thebrackets within the notches.

3. A furnace door as in claim 1 wherein the shelves are fixed by Weldingto the rear surface of the frame.

4. A furnace door comprising a hollow frame with a central recess,shelves attached to the door within the recess and having outer edges ina common plane, and metal clad magnesite brick fastened to the shelvesWithin the recess and terminating in the common plane forming a liningof molten metals of the shelf edges, the metal of the metal clad brickwhich is exposed, and the magnesium of the brick across the heat exposedsurface of the door.

5. A furnace door comprising a hollow panel, means for circulating acoolant through the panel, a lining of metal-clad magnesite brick layedin courses across the face of the panel for exposure to furnace heat,and shelves positioned between the brick courses and fastened to themetal of the metal-clad brick and to the face of the panel fastening thelining in place on the door panel, the shelf edges and the metal cladbrick sides directly exposed to heat of the furnace being in a commonplane and fused together with magnesium of the brick to form a liningsurfaoe of molten metals.

6. A furnace door comprising a hollow vertical panel with a continuousrearwardly-directed hollow marginal portion opening into the hollowvertical panel, the door having a re-entrant portion bounded by thecontinuous rearWardly-directed hollow marginal portion and the rear faceof the panel, an inlet pipe fixed to the door hollow marginal portionand extending from without the door into the hollow portion andterminating above the bottom of the door, an outlet conduit opening intothe hollow marginal portion opposite the inlet pipe, refractorymagnesite brick layed in courses within the re-entrant portion, andmetal shelves fastened to the rear face of the panel and positionedbetween courses of the brick and fixed to the brick by fusion of themagnesium of the brick to the shelves at their outer edges, the shelfouter edges lying in a plane which includes the exposed sides of thebrick and fused therewith to form a molten lining surface with meltedmagnesium of the brick.

7. A furnace door comprising a front plate, a rear plate spaced from thefront plate, the marginal portions of the plates being rearwardly turnedand joined to form a hollow peripheral door portion opening into thespace between the front and rear plates, an inlet pipe connected to thedoor and extending Within the peripheral door portion, an outlet conduitconnected to the door in communication with the hollow peripheral doorportion, the rear plate and its marginal portion forming a re-entrantportion in the rear face of the door, refractory metal-clad magnesitebrick layed in courses within the re-entrant portion nesite brick layedin courses within the rte-entrant portion, metal shelves fastened to therear face of the door within the recess and positioned between thelayers of brick and extending to a plane including the exposed face ofthe metal of the clad brick, the magne-site of the brick, the exposedmetal of the metal of the brick, and the exposed edges of the shelvesbeing melted to form a surface layer across the recess with the rate ofmelting of the materials being regulated by the amount of coolingeffected by passing a coolant through the inlet pipe and hollow portionto the outlet pipe.

References Cited by the Examiner UNITED STATES PATENTS 2,325,945 8/43Fuchs 122-498 2,426,568 8/47 Sontz 1l0l73 2,475,102 7/49 Longacrell0-173 2,512,439 6/50 Richards -180 2,673,534 3/54 Robinson 1101732,764,887 10/56 DAmbly 1101 2,781,006 2/57 Heller 1l0-1 FREDERICK L.MATTESON, JR., Primary Examiner.

PERCY L. PATRICK, ROBERT A. OLEARY,

Examiners.

1. A FURNACE DOOR COMPRISING A RIGID HOLLOW FRAME WITH A PLANAR REARSURFACE HAVING A RECESS, THE FRAME BEING OF A SIZE AND CONFIGURATION TOSPAN AN ACCESS OPENING JOF A FURNACE IN COMMUNICATION WITH THE HEATINGZONE OF THE FURNACE, THE RECESS BEING OF A DEPTH EQUAL TO A DIMENSION OFA CLAD REFRACTORY BRICK, METAL SHELVES ATTACHED TO THE REAR SURFACE OFTHE FRAME AND WITHIN THE RECESS AT VERTICALLY-SPACED INTERVALS WITH THESHELF OUTER EDGES BEING IN A COMMON PLANE WHICH INCLUDES ONE WALL OF ABRICK PLACED THEREON, THE SHELVES BEING OF LENGTHS TO SPAN THE RECESSAND OF WIDTHS SUBSTANTIALLY EQUAL TO THE DEPTH OF